Residual Shear Strenght, Slake Durability and Mineralogy in Clay Shale and Rock on Ungaran - Salatiga Toll Road, Bawen, Semarang

INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 9, ISSUE 10, OCTOBER 2020 ISSN 2277-8616 Residual Shear Strenght, Slake Durability And Mineralogy In Clay Shale And Rock On Ungaran - Salatiga Toll Road, Bawen, Semarang

Bambang Pardoyo

Abstract: The Bawen - Semarang Toll Road, located in Central Java, is a road that connects Bawen District to Semarang Regency. Geologically, the location of the Indonesian territory, which is traversed by three main tectonic plates, namely the Europe-Asia, India-Australia and the Pacific Plate, makes Indonesia a lot of active volcanoes and prone to disasters. The purpose of this study is the physical, mechanical and mineralogy characteristics of clay shale and rock. The methodology is the sample used in sun-exposed conditions and the tests properties rock, direct shear test, durability test, and mineralogy test. The conclusion from the results of the analysis on direct shear, it is found that the value of the residual effective shear angle ('r) ranges from 4.77 - 9.78 ° and the effective cohesion value (c ') is 5.97 - 17.95 kN/m2 and can it is said that in geological engineering for materials that are susceptible to weathering processes, rock resistance based on the slake durability classification, samples L 1 and L 4 are classified as Low Durability, so it can be interpreted that the sample is very prone to weathering when exposed directly to weather changes ,, L 2 is classified Medium Durability, and L 3, are classified as Medium High Durability, so that it can be interpreted as L 2 and L 3, it takes a long time to experience the weathering process Meanwhile, the mineralogy composition of the residual clay shale by XRD testing was obtained the composition of 24.7% montmorillonite, 31.2% kaolinite and 10.3% mica..

Keywords : Residual, Clay Shale, Slake Durability, Shear Strenght, Mineralogy —————————— ——————————

1. INTRODUCTION First, soil tests were carried out to determine the physical and Toll Bawen - Semarang, located in Central Java, precisely in mechanical characteristics of clay shale and rock in the book Bawen sub-district dan geologically, the location of the Principles of Geotechnical Engineering [3]. Residual shear Indonesian territory, which is traversed by three main tectonic strength consists of two parameters namely residual shear plates, namely the Europe-Asia, India-Australia, and the angle (ф'r) and residual cohesion (c'r) which can be used for Pacific Plate, makes Indonesia many active volcanoes and long-term analysis of slope stability and excavation[4], second, prone to disasters. This different relief is caused by the the rock resistance test was first proposed by [5] assessing geological activity of the earth it self, plate moves (converges) the resistance caused by rock samples to weaken and / or or moves away (diverges), resulting in a push or pull on the disintegration when cycled from drying and wetting with rock on the surface. Factors controlling mass movement standard measurements of the weight of loss of rock include geomorphology, geological structures, rock lithology, properties when repeatedly rotated through the interface. air land use, and geohydrology[1]. Based on its formation, the and water with Gamble's Slake Durability Classification[6]) in rocks are divided into 3 (three) major groups according to [2], Table 1 and third, mineral tests with XRD. namely: igneous rock, metamorphic rock and sedimentary rock.

Table 1 Gamble's Slake Durability Classification[6]

Durabilitas SDI 1st Cycle SDI 2nd Cycle Very High Durabilty > 99 >98 High Durabilty i 98 – 99 95 – 98 Medium High Durabilty 95 – 98 85 – 95 Medium Durabilty 85 – 95 60 – 85 Low Durabilty 60 – 85 30 – 60 Very Low Durabilty < 60 0 – 30

The strength of the clay shale flakes drops dramatically until 2. MATERIAL AND METHODS they become very soft when they are wet and submerged. Clay shale test samples were taken at five points, located on When clay shale is subjected to repeated loads, its strength the Semarang - Bawen toll road. The real conditions of all gradually decreases from very soft until it reaches residual samples taken have been exposed to sunlight in Figure 1 and strength [7], [8], [9], conducted research on clay shale soils, the coordinates of each sample location point in Table 2. with residual shear angle values. The test samples were taken from clay shale or rocks exposed to sunlight, already weathered, how to store

______samples without and with paraffin at a depth of - 0.00 - 0.50 m. Then the following tests were carried out : water content[10], Specific Gravity [11], Atterberg Limit Test  Bambang Pardoyo, Universitas Diponegoro. E-mail: [12], [13], Slake Durability Test – ASTM D4644-08 (ASTM [email protected] International, 2008), Direct Shear Test Residual [15].

Figure 1 Sampling Location

Table 2 Coordinates of test soil sample locations

Sample South Latitude East Longitude Location L1 7°14'10.0" 110°27'13.2" Kandangan Village

L2 7°14'12.0" 110°27'13.3" Kandangan Village

L 3 7°14'00.7" 110°27'11.5" Kandangan Village

L 4 7°14'11.5" 110°27'10.6" Kandangan Village

3. RESULTS AND DISCUSSION The results of the rock properties index testing carried out on the specimen from the point of extraction at L 2 and L 3 are shown in Table 3

Table 3 Results of rock properties index testing L 2 and L 3

TTK 2 TTK 3 Sample Paraffin Non-Paraffin Paraffin Non-Paraffin Kadar Air (%) 13,30 9,24 12,25 8,20

Specific Gravity (Gs) 2,730 2,707 2,833 2,821

Gravel (%) 67,41 63,04 71,99 66,86

Sand (%) 32,59 36,96 28,01 33,14 Silt and Clay (%) 1,33 1,28 1,87 0,84 Pass sieve No. 4 (%) 64,07 82,05 64,05 66,17 Pass sieve No. 10 (%) 32,59 36,96 28,01 33,14

Pass sieve No. 40 (%) 20,93 13,45 13,61 18,87 Pass sieve No. 200 (%) 1,33 1,28 1,87 0,84 D10 (mm) 0,153 0,200 0,284 0,157 D30 (mm) 1,500 1,500 2,250 1,160

D60 (mm) 4,350 3,000 4,500 4,100

Cu 44,231 16,750 18,182 35,333 Cc 2,261 2,522 1,823 2,361

Referring to Table 3, the USCS Classification System, the gravel, and sand.[3] and the results of testing the GW group, i.e. well-graded gravel and a mixture of sand properties index of clay shale carried out on the test object gravel, contains little or no fine grains. AASHTO from the point of collection at L 1 and L 4 are shown in Classification System, group A-1-a, namely crushed stone, Table 4.

Table 4 Results of clay shale properties index testing L 2 and L 3

TTK 1 TTK 4 Sample Paraffin Non-Paraffin Paraffin Non-Paraffin

Kadar Air (%) 18,38 13,25 16,39 11,63

Wet Density (ɣb) 2,091 2,08 2,098 2,094

Specific Gravity (Gs) 2,66 2,65 2,63 2,65 Liquid Limit (%) 57,63 57,85 57,85 57,00

Plastic Limit (%) 29,31 29,74 29,5 28,58 Plasticity Index (%) 28,32 28,11 28,35 28,42 Pass sieve No. 40 (%) 100 100 99,9 99,89

Pass sieve No. 200 (%) 97,89 91,83 89,86 91,69 Clay fraction(%) 78,26 70,71 75,87 53,54

Based on Table 4, the USCS Classification System, the OH [3]and if the LL and PI values are plotted into the Plasticity group, is an organic clay with moderate to high plasticity. The Graph according to Das and Sobhan (2014) from Table 4, it AASHTO Classification System, group A-7-6, i.e. clay soil. can be seen in Figure 2 and Figure 3

70 60 CH

(%) 50 40 CL 30

20 MH Plasticity Index Index Plasticity 10 ML 0 0 10 20 30 40 50 60 70 80 90 100 Liquid Limit (%) A-line PI = 0.73(LL-20) Batas LL L 1 L 4

Figure 2 Plasticity graph of L 1 and L 4 samples according to USCS Classification.[3]

Figure 3 Plasticity graph of L 1 and L 4 samples according to AASHTO Classification.[3]

The residual direct shear test is only carried out on clay shale with 15 x Blow, 1PL + 5% 15 = Location 1 at water content soil only aims to determine the values of the effective Original limit plasticity + 5% moisture content with 15 x Blow , parameter of residual shear strength, where the permeability is 1PL + 10% 15 = Location 1 at water content Original limit low, i.e. the test is carried out with the slow test type.. The plasticity + 10% moisture content with 15 x Blow, that's the notation used in the sample code, PL = Plasticity Limit, same thing as in Location 4 on Table 5. 1PL15x = Location 1 at water content Original limit plasticity

Table 5 The residual value of effective cohesion (c ') and effective shear angle ('r) for 15 times the blow(L.1,L 4)

'r c' Sample (°) (kN/m²)

1PL15x 0 9.85

L.1 1PL+5%15x 8.08 8.88 1PL+10%15x 5.43 10.11

4PL15x 9.78 17.12

L.4 4PL+5%15x 8.27 16.98 4PL+10%15x 7.44 17.95

Likewise the notation for both locations on 25x blows on Table 6

Table 6 The residual value of effective cohesion (c ') and effective shear angle ('r) for 25 x blow(L 4) [8]

'r c' Sample (°) (kN/m²)

1PL25x 6.81 5.97

L L 1 1PL+5%25x 5.80 7.69 1PL+10%25x 4.77 9.37

4PL25x 8.07 15.52

L L 4 4PL+5%25x 7.25 13.51 4PL+10%25x 6.43 12.59

Test results of mechanical properties of clay shale soils, residual shear angles are plotted graphs in Figure 4, figure 5, figure 6, figure 7 [7] and Figure 8, figure 9, figure 10, figure 11[8], on 15x and 25x blow.

Figure 4 The residual value of effective cohesion (c ') and effective shear angle ('r) for 15 x blow(L 1)[7]

Figure 5 The residual value of effective cohesion (c ') and effective shear angle ('r) for 15 x blow(L 4) [7]

Figure 6 The residual value of effective cohesion (c ') and effective shear angle ('r) for 25 x blow(L 1) [7]

Figure 7 The residual value of effective cohesion (c ') and effective shear angle ('r) for 25 x blow(L 4) [7]

The results of the mechanical properties of clay shale soil, the remaining shear angle according to Gartung (1966) in the residual area

Figure 8 The residual value of effective cohesion (c ') and effective shear angle ('r) for 15 x blow(L 1) [8]

Figure 9 The residual value of effective cohesion (c ') and effective shear angle ('r) for 15 x blow(L 4) [8]

Figure 10 The residual value of effective cohesion (c ') and effective shear angle ('r) for 25 x blow(L 1)[8]

Figure 11 The residual value of effective cohesion (c ') and effective shear angle ('r) for 25 x blow(L 4)[8]

While the results of the mechanical properties of clay shale mechanical properties of clay shale soils, residual shear soil, the remaining shear angle according to Skempton angles, are plotted graphs in Figure 8. [9] (1985), experienced significant changes The results of

Figure 12 Plotting score shear angle on the graph of effective strength and shear strength [9]

The results obtained indicate that the relationship between the classification with and without paraffin according to Gamble's liquid limit and the residual shear angle is directly proportional Slake Durability Classification by Goodman (1980) in Table 7 to the test according to Stark and Eid (1994), at the position and Table 8. [6] below the graph. From the research results obtained rock

Table 7 Paraffin Slake Durability Test Results[6]

Weight Weight % nd Initial Weight st Restrained % Lasted 2 Sample Restrained 1 nd Restrained (gram) 2 Cycle st Cycle Calcification Cycle (gram) 1 Cycle (gram) L 1 568.43 437.355 172.97 76.964 30.438 Low durability Medium L 2 527.865 452.86 322.675 85.812 61.154 durability Medium high L 3 565.925 547.335 538.695 96.723 95.187 durability L 4 537.065 417.985 169.35 77.861 31.574 Low durability

Table 8 Non-Paraffin Slake Durability Test Results[6]

Weight Weight % Initial Weight Restrained % % Lasted Sample Restrained 1st Restrained (gram) 2nd Cycle st 2nd Cycle Calcification Cycle (gram) 1 Cycle (gram) 1 556.33 420.37 167.395 75.536 30.087 Low durability Medium 2 492.295 400.11 298.36 81.278 60.608 durability Medium high 3 576.115 556.235 541.65 96.556 94.008 durability 4 570.96 432.77 175.52 75.818 30.768 Low durability

From the mineralogy results of the XRD test at the Undip Integrated Laboratory, it can be seen in Figure 15

Figure 13 UNDIP Integrated Laboratory XRD Test Results

The data from mineralogy study (X-Ray Diffraction), can be [7] E. M. Gartung, ―Excavation in Hard Clays of The read through the Match! Program. Copyright © 2003-2014 Keuper Formation,‖ 1986, doi: 10.1016/0148- CRYSTAL IMPACT, Bonn, Germany obtained a 9062(87)92601-5. composition of 24.7% montmorillonite, 31.2% kaolinite and [8] A. W. Skempton, ―Residual strength of clays in 10.3% mica. landslides, folded strata and the laboratory,‖ Geotechnique, 1985, doi: 10.1680/geot.1985.35.1.3. 4. CONCLUSION [9] T. D. Stark and H. T. Eid, ―Drained Residual Strength of Cohesive Soils,‖ J. Geotech. Eng., The conclusion from the results of the analysis on direct 1994, doi: 10.1061/(ASCE)0733- shear, it is found that the value of the residual effective 9410(1994)120:5(856). shear angle ('r) ranges from 4.77 - 9.78 ° and the effective [10] ASTM International D2216-19, ―ASTM D2216-19 - cohesion value (c ') is 5.97 - 17.95 kN / m2 and can it is Standard Test Methods for Laboratory said that in geological engineering for materials that are Determination of Water (Moisture) Content of Soil susceptible to weathering processes, rock resistance based and Rock by Mass,‖ ASTM Int., p. 7, 2019, doi: on the slake durability classification, samples L 1 and L 4 10.1520/D2216-10. are classified as Low Durability, so it can be interpreted that [11] ASTM International D854 - 17, ―D854 - 17 Standard the sample is very prone to weathering when exposed Test Methods for Specific Gravity of Soil Solids by directly to weather changes ,, L 2 is classified Medium Water Pycnometer,‖ Am. Soc. Test. Mater., 2017. Durability, and L 3, are classified as Medium High [12] ASTM D4318 - 17e1, ―Standard Test Methods for Durability, so that it can be interpreted as L 2 and L 3, it Liquid Limit, Plastic Limit, and Plasticity Index of takes a long time to experience the weathering process Soils,‖ 2017, doi: 10.1520/D4318-10. Meanwhile, the mineralogy composition of the residual clay [13] ASTM International D 7928-17, ―Standard test shale by XRD testing was obtained the composition of 24.7% method for particle-size distribution (Gradation) of montmorillonite, 31.2% kaolinite and 10.3% mica. fine-grained soils using the sedimentation (Hydrometer) Analysis (ASTM D7928),‖ ASTM, REFERENCES 2017, doi: 10.1520/D7928-16. [1] D. Karnawati, ―Dwikorita Karnawati. 2005. Bencana [14] ASTM International, ―ASTM D4644-08 Standard Alam Gerak Massa Tanah di Indonesia dan Upaya Test Method for Slake Durability of Shales and Penanggulangannya. Yogyakarta,‖ 2005. Similar Weak Rocks,‖ ASTM Int., 2008. [2] L. Zhang, Drilled Shafts in Rock: Analysis and [15] ASTM Standard D3080/D3080M - 11, ―Direct Shear Design. 2004. Test of Soils Under Consolidated Drained [3] B. M. Das and K. Sobhan, ―Principles of Conditions,‖ 2012, doi: 10.1520/D3080. Geotechnical Engineering, SI Version,‖ Animal Genetics, 2014. . [4] K. H. Head and R. J. Epps, Manual of Soil Laboratory Testing, vol. 21, no. 3. 2015. [5] J. A. Franklin and R. Chandra, ―The slake-durability test,‖ Int. J. Rock Mech. Min. Sci., 1972, doi: 10.1016/0148-9062(72)90001-0. [6] R. Goodman, ―Introduction to Rock Mechanics,‖ Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 1980.